What might it mean to say that language is innate or, alternatively, that language must be learned? This proposal attempts to articulate the question in terms that lend themselves to experimental investigation, asking which aspects of language development are so over-determined that they will appear even under learning conditions that vary widely from the norm. The participants are deaf children whose hearing parents have not yet exposed them to sign language, and whose hearing losses are so profound as to preclude acquisition of spoken language. Despite their lack of an accessible conventional language model, deaf children in the U.S., China, Turkey and Spain develop gesture systems that are structured in language-like ways. Where do these structured gesture systems come from? One candidate is the gestures hearing adults produce as they talk. But the gestures that hearing speakers produce as they communicate with their children lack language-like properties. Only when hearing speakers are asked to produce gesture without speech do their gestures take on language-like structure. The deaf children in previous studies were being educated orally and their hearing parents always produced gestures along with speech. Recent observations of hearing parents of deaf children in Nicaragua have revealed that these hearing parents often produce gestures without speech when communicating with their deaf children. Will this gestural input, which is likely to be language-like in structure, lead deaf children to construct a more linguistically sophisticated gesture system? Comparing Nicaragua to the other four cultures offers a unique opportunity to examine whether and how the gestures of hearing speakers influence the gesture systems developed by deaf children. The proposed project has 4 aims: (1) To characterize the gestures hearing adults produce with speech and without it in Nicaragua where deaf children are likely to receive gesture-without-speech as input to their gesture systems, and in Spain, Turkey, China, and the U.S. where deaf children primarily receive gesture- with-speech as input;(2) To determine whether gesture systems created by Nicaraguan deaf children are more complex than gesture systems created by Spanish, Turkish, Chinese and American deaf children;(3) To determine whether, in each of these cultures, hearing children, who interpret the gestures hearing speakers produce in the context of speech, use gestures differently from deaf children, who must interpret these same gestures without access to speech;(4) To explore a potential cognitive basis for the structure found in the deaf children's and hearing adults'gestures without speech, using a recently developed technique. In addition to their theoretical importance, the results will have practical significance. Informed of the capacities children themselves bring to language-learning, educators may be better able to help deaf children or hearing children with language disabilities learn a conventional language, be it signed or spoken.